Advanced Materials Research Vols. 588-589

Abstract: The geometries, stabilities, electronic and magnetic properties of small Gd_nO₃ (n=1-5) clusters have been systematically studied by using density functional theory with the generalized gradient approximation. We found that the Gd atoms and O atoms in Gd_nO₃ clusters prefer three and two coordination, respectively, which origin from the electronic configurations of Gd and O atoms. The results show that Gd₂O₃ cluster is more stable than its respective neighbors, which is reflected from its high average binding energy and high HOMO-LUMO gap. In addition, we calculate the magnetic properties of Gd_nO₃ clusters. The local magnetic moments of the Gd atom in the Gd_nO₃ clusters exhibit a weak dependence on the O atoms, which are slightly enhanced with the increasing of the number of Gd atom.

Abstract: Simulate sewage were used in an anaerobic-anoxic-aerobic biological nutrient removal system(A²O process), by observing the pHs in different compartments and its reflected changes in nitrogen and phosphorus removal, studied on the effects of different pHs on the removal of pollutants. The experiments indicates that the anaerobic phosphorus release showed the main performance of the decline of pH, denitrification in anoxic zone caused the rise of pH, uptake of phosphate in the aerobic zone mainly caused the continuous rise of pH. There is no evidently changes in COD removal, ammonia nitrogen get the highest removal as the pH value was between 8.0-8.5, when pH was at 6.5-7.5, the TN have the maximum removal rate, TP can keep in a high level when the pH was above 6.0.

Abstract: With the rapid economic and social development of China, the attention to environment issue is higher and higher. Current, toxic and hazardous substances polycyclic aromatic hydrocarbons (PAHs) has been detected in the air, water, sediments of the river (or lake) and soil. Part of these PAHs come from (1) volatile of PAHs in solids phase or liquids phase in raw coal ,(2) raw coal incomplete combustion (3) PAHs hydrolyze in a reducing atmosphere. As the basis of PAHs discharging in the process of coal using, it is necessary to summary extraction, purification, analysis of the PAHs in raw coal, conclude species and content of PAHs in raw coal, analysis the impact factors of PAHs distribution, discovered the deficiencies in current research and the future research direction.

Abstract: Dissolved Oxygen (DO) is one of critical factors influencing substrate degradation and nitrification rates in activated sludge process. A two-step nitrification model describing the aeration period of the sequencing batch reactor (SBR) operation is developed. Parameter estimation of this model using the DO data determine the stoichiometry and kinetic parameters as well as the initial value of main nutrients, including readily biodegradable substrate, ammonia, nitrite and nitrate. Only if the parameter estimation is implemented, reaction related substrates can be predicted if new initial values are given. With optimal DO data, this paper pointed out that without initial value monitoring, both of the parameter estimation and prediction of the main nutrients profiles can be done through a simple method based on a global parameter estimation algorithm.

Abstract: After carbonized at different temperatures, agricultural waste-rice-husk, becomes carbonized, which has further been modified at different pH values. Through some static tests, we studied the treatment efficiency for the wastewater--containing mechanical lubricants- by the carbonized rice husk at different amounts of carbonized rice husk, different treatment times and different processing temperatures. The results showed that the optimal carbonization temperature of the rice husk is around 500°C, and the pH modification’s impact was not notable. The optimal conditions of the treatment of wastewater containing 10% mechanical lubricant (volume percentage, made by Shell), were found at the amount of 6g/l carbonized rice husk, with the processing time of 15 min, and the temperature of 15°C. Under that condition, the oil removal rate could reach 88.38% and adsorption capacity of the carbonized rice husk is 22.32ml/g; however, when referring to Mobil (model: 20W-40), the oil removal rate could reach 94.24%, which is considerably superior to other kinds adsorbents. Treatment of oily wastewater by carbonized rice husk is in conformity with the second order kinetic equation, and the related coefficient is 0.9671; besides, the adsorption thermodynamic analysis shows that the adsorption process can be spontaneous at the low temperature, which therefore can be used for the oily waste water treatment.

Abstract: Extraction of humic acid from lignite is an efficient method of comprehensive utilization of resource. Based on the trial test, the main factors such as extracting time, concentration of alkaline solution and extracting temperature, which were chosen as parameters to access their effects on extracting rate and identify the optimal conditions by using RSM. Box-behnken central composite design and advanced mathematics were applied to achieve the mathematical model that could predict the response (extraction rate). The results showed that the best technological conditions could be obtained， when extracting time was 82.32min, temperature was 65.83°C and the concentration of sodium hydroxide was 0.94mol/L. Prediction model showed that the maximum extracting rate was 89.19% and the actual experiment obtained a similar result.

Abstract: This paper has established geometry model of the rigid-plastic Finite Element Model (FEM) basing on the foundation of similarity theory. It has simulated and analyzed the material of ASTM-Gr.D used by finite element analysis software of metal plastic DEFORM with different negative clearance values blanking, which obtains the caver of the different negative clearance values with roll-over with sheared zone with punching load. According to the result of simulation, it has made an experiment on the ASTM-Gr.D of 2.0(mm) thickness with the different negative clearance, and obtained samples with sheared well and no burr, which summarized that it could achieve no burr in fine blanking when the values of negative clearances value took -0.1 ~ -0.3mm.

Abstract: Whether zhuan 8AG type bogie can achieve the requirement of speed increasing, which have become an important question need to face and research for the railway sectors. The residual life of zhuan 8AG side frame is studied by interior fatigue test that equivalent to the actual running conditions. The interior fatigue test data was processed by Weibull distribution with 3 parameters. The point estimation and the interval estimation of the safe life were given. The fitting result indicate that, the test date conform the Weibull distribution very well. Using generalized P-S-N formula and correctional two dimensional Miner’s rule derivate the residual running mileage prediction formula of zhuan 8AG side frame based on the interior test and the actual line test. The point estimation and interval estimation of residual life are computed under certain reliability and confidence. The estimation results show that, under 95% confidence and 99.9% reliability, the zhuan 8AG side frame has 10.6 years residual life at least. Thus, its’ prospect of applications by increasing speed is optimistic. As a result of some difference about forces on side frame between internal test and actual operation, high incidence area of crack in test is different from in reality. In this fatigue test, breakages are all the C position of side frame. However, the highest probability of crack occurred position in the top surface of pedestal, which total crack numbers accounted for 50% of total crack numbers on side frame in actual running. The paper recommends that the results between internal fatigue and actual operating should be analyzed comparatively, so as to simulate the actual working conditions more realistic.

Abstract: Electrochemical behaviors of Ce³⁺/Ce⁴⁺ couple in mixed acid (H₂SO₄ and CH₃SO₃H) were investigated on Pt electrode. Polarization curves and electrochemical impedance spectroscopy (EIS) were used to optimize mixed acid composition, and the mixed acid consisting of 1.0 M methanesulfonic acid (MSA) and 0.8 M sulfuric acid is singled out as the optimum electrolyte. Subsequently, the effects of current density and electrolyte temperature on the electrochemical oxidation of Ce³⁺ to Ce⁴⁺ were researched. A 92.2% current efficiency was achieved at 40 mA•cm^-2 in cerium (III) solution with the optimum mixed acid electrolyte above at 313 K. It can satisfy the application of mediated electrochemical oxidation process with Ce³⁺/Ce⁴⁺ mediator.

Abstract: In this article, micro investigation of the cement stone under sulfate erosion is carried out by using SEM (Scanning Electron Microscope). The XRD method is also employed to semi-quantitatively analyze the erosion product. The cement stones whose water-cement is 0.45, 0.55, 0.65, respectively, immersed in sulfate solution whose sulfate ion concentrations is 0%, 3%, 4%, 5%, 6%. After different immersion time of 24 days, 45 days and 60 days, the microstructure of samples is detect by the SEM. The energy-dispersive X-ray analysis (EDX) is taken to determine the general elements in samples. The XRD method is employed to semi-quantitatively determine the weight percents of ettringite and gypsum in cement stone samples. Through comparative analysis, it tries to point out how the sulfate ion and water-cement ratio will affect the erosion products.